Hosted virtual server services allow users to instantiate virtual servers running software specified by the users without requiring a customer to own or manage the hardware underlying the virtual server instances. Virtual server services, including, for example, Amazon EC2, may enable users to instantiate a number of virtual servers of a variety of different configurations to match their needs.
Many virtual server services allow instantiation of virtual servers from bootable images provided by users. These images may contain the set of desired server software of the users. Some virtual server services allow the remote instantiation of virtual servers from bootable images provided by users, such as through a published API or a web interface. The remote instantiation capabilities in principle allow a user to scale up or down the number of instantiated virtual servers based on changing demand or other factors. However, it is typically not practical to personally monitor servers, decide when to launch additional servers, and configure them manually.